Free Deep-Reasoning AI for Math and Science: GPT 5.6 Terra

Some problems can't be answered fast — they need to be worked through. GPT 5.6 Terra is OpenAI's deep-reasoning model with serious mathematical logic and scientific problem-solving chops. And it's free with no signup on Toolxz AI Chat.

What Terra is best at

Multi-step reasoning where a wrong turn early ruins everything:

"Walk through this probability problem step by step. Show your work at each stage: [problem]"

"Derive the time complexity of this algorithm formally, don't just state it: [code]"

"Check my physics reasoning — where does this derivation go wrong? [working]"

The key phrase is "show your work." Deep-reasoning models do their best when you demand the steps, not just the answer.

How to prompt it

Be explicit that you want rigor: "be rigorous," "verify each step," "flag any assumption." Terra will slow down and check itself — that's the point.

Try it free

Chat with GPT 5.6 Terra on Toolxz — no account, no API key. Also there: Claude Sonnet 5, GPT 5.6 Sol, Claude Fable, GLM 5.2, Kimi K3.

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Founder of Toolxz (toolxz.com) — 45+ free browser-based tools. I write about practical AI tooling and developer workflows.